function hiircb_hui, T

  T_HI = 1.57807d5
  lambda = 2.d0 * T_HI / T

  rate = 2.753d-14 * lambda^1.500d0 / $
         ( 1.d0 + (lambda/2.740d0)^0.407d0 )^2.242d0

  return, rate

end
